It just feels like 1000 feet!!
and at one point it descends almost 1000 ft
Small correction regarding this statement. It actually descends around 550 ft before going up towards Mahogany Flat. I verified with my altimeter twice :)
I would just like to add, that the George Creek approach to Mt Williamson (in April or early May) and a return from the summit, is one of the great (if not the best) ski trips of the High Sierra. The ski from the summit is over 10,000 feet long and if one hits the conditions just right, you can ski almost to your car. Unforgetable and recommended for backcountry skiers looking for great Sierra experience.
A flash flood last summer (2013) washed out a section of the Shepherd Pass trail at approximately 10,000', just below Anvil Camp. It is necessary to hike approximately 100 feet upslope from the trail to cross near a large rockfall. There is a second washout a little higher as well, but is easily bypassed and is cairned.